Vehicle windows sometimes include thin films through which ohmic heating current may be applied to defrost the windows. Impact from road debris and other objects can damage windows. For example, a thin film layer in a window that is used for heating the window may become damaged. When this damage is left undetected, there is a risk that the thin film will corrode due to exposure to moisture or that the thin film may not perform properly. Windows that develop small cracks may also be prone to more extensive cracking.